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AS Unit F321: Atoms, Bonds and Groups

Module 1: Atoms and Reactions

1.1.1 Atoms
a) All elements are made up from atoms. Atoms are made up from 3 types of particles, protons,
neutrons and electrons. Electrons have a -1 relative charge, and Protons have a +1 charge, whilst
Neutrons are…

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concentrated and dilute are descriptive terms for the amount, in mol, of dissolved solute in a solution.
Concentrated is a large amount of solute per dm3 and dilute is a small amount. Concentrated acids
usually have a concentration of greater than 10 mol dm3.

1.1.3 Acids
a) Acids release H+…

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1.1.4. Redox

a) An oxidation number is a measure of the number of electrons that an atom uses to bond with
atoms of another element. The rules are set out in the table below:

Species Oxidation Number Examples

Uncombined element 0 C,Na,O2, P4

Combined oxygen -2 H2O, CaO

Combined hydrogen…

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Module 2: Electrons, Bonding and Structure

1.2.1 Electron Structure

a) The first ionisation energy of an element is the energy required to remove one electron from
each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions. Successive
ionisation energies are a measure of the…

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g) A sub-shell is a group of the same type of atomic orbital (s, p, d or f) within a shell. The sub-shells
within a shell have different energy levels. Within a shell the sub-shell energies increase in the
order s, p, d and f.
h) The order of sub…

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j) Predict the shapes of molecules similar to those seen here
k) Electronegativity is a measure of the attraction of a bonded atom for the pair of electrons in a
covalent bond.
l) Because the atoms in some compounds are different, they differ in their Electronegativity. The Cl
atom in…

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solid lattice breaks down and the ions can move ­ so can thus conduct electricity. Ionic lattices
dissolve in polar solvents, such as water because the solvent surrounds each ion to form a solution.
r) Elements and compounds with covalent bonds are either simple molecular lattices or giant
covalent lattices.…

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d) Across each period there is a general increase in the ionisation energy due to the presence of
more protons. Electrons are added to the same shell, so the outer shell is drawn inwards slightly,
reducing the atomic radius, and the electron shielding will not change. At the start of…

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c) Disproportionation is a reaction in which the same element is both reduced and oxidised. An
example is the use of chlorine in water to kill bacteria. It reacts with water, forming HCl and HClO,
and it is both oxidised and reduced. In aqueous sodium hydroxide it reacts to form…


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